Which drug classes can precipitate lithium toxicity?

• A. NSAIDs
• B. ACE inhibitors
• C. Thiazide diuretics
• D. All of the above

Answer: (D)

Lithium is cleared by the kidneys, and many drugs can raise its levels by altering renal handling or GFR. NSAIDs reduce renal prostaglandins, lowering renal perfusion and lithium clearance, which can push lithium toward toxicity. ACE inhibitors dilate the efferent arteriole and can decrease GFR and increase proximal tubule reabsorption of sodium and lithium, raising lithium levels. Thiazide diuretics cause volume depletion and hyponatremia, promoting greater proximal reabsorption of sodium and lithium. Because each of these classes can independently precipitate lithium toxicity, the option that includes all of them is correct. If such agents are needed in a patient on lithium, monitor lithium levels closely and adjust therapy as needed.